Video output consumes a significant amount of power for a laptop or desktop computer. Other computing systems and electronics devices—such as handheld computing devices, cellular telephones and music players—also devote a large fraction of their power budget to video. Power consumption sensitivity increases for portable devices that rely on a battery having limited energy supply.
Currently, commercially available power conservation techniques alter an entire image at once. Most techniques uniformly shut down a display or unvaryingly modify all video output in an image after some predetermined time. These techniques usually impede a person's ability to see graphics items and further use the computing device. Frequently, a person responds by reactivating the entire display—at full power. As a result, little power is saved.